Movable magnet transmitter for inducing electrical current in an implanted coil

Abstract

An external power head is energized by a motor causing movement of an element that produces a varying magnetic field, thereby inducing power in an implanted receiver coil within a patient's body. The external power head includes either one or more moving permanent magnets, or one or more moving elements that vary the magnetic flux coupled to the implanted receiver coil. As a result of the varying magnetic field experienced by the implanted receiver coil, an electric current flows from the implanted receiver coil to energize an implanted medical device.

The invention in which an exclusive right is claimed is defined by the following: 
     
       1. A method for generating a varying magnetic field to couple energy to an implanted receiver coil, comprising the steps of: (a) generating a magnetic field;   (b) coupling a driving force to an element so that the element is movable; and   (c) moving the element with the driving force in a reciprocating motion to vary the magnetic field coupled to the implanted receiver coil, variation of said magnetic field coupled to the implanted receiver coil causing a varying electrical current to be induced in the implanted receiver coil.   
     
     
       2. The method of claim 1, wherein a source of the driving force is disposed remote from where the magnetic field is generated and is coupled to the element through a driven shaft. 
     
     
       3. The method of claim 1, wherein said element is moved sufficiently fast to magnetically couple with an air core implanted receiver coil. 
     
     
       4. The method of claim 1, wherein the magnetic field is generated with at least one permanent magnet. 
     
     
       5. The method of claim 4, wherein the permanent magnet comprises a rare earth alloy. 
     
     
       6. The external transmitter of claim 5, further comprising the step of providing an electrical current flow through a plurality of turns of a conductor wound around said at least one permanent magnet to selectively adjust a maximum value of the magnetic field produced by said at least one permanent magnet, said electrical current producing a magnetic field that either increases or reduces the magnetic field generated said at least one permanent magnet support is rotated, a separation of said plurality of permanent magnets being controlled to adjust the magnetic field coupled to the implanted receiver coil. 
     
     
       7. The method of claim 4, wherein the element that is moved comprises said at least one permanent magnet. 
     
     
       8. The method of claim 7, further comprising the step of enhancing magnetic flux linkage between magnetic poles of the permanent magnet and the implanted receiver coil by providing a flux linkage bar for coupling a magnetic field from a pole of the permanent magnet into the implanted receiver coil, enabling the permanent magnet to be displaced from the implanted receiver coil. 
     
     
       9. The method of claim 1, further comprising the step of selectively varying a maximum magnetic field intensity coupled with the implanted receiver coil. 
     
     
       10. The method of claim 9, wherein the step of selectively varying the maximum magnetic field intensity comprises the step of positioning the element relative to the implanted receiver coil to control the magnetic field coupled to the implanted receiver coil. 
     
     
       11. The method of claim 9, wherein the step of selectively varying the maximum magnetic field intensity comprises the step of changing a speed with which the element moves. 
     
     
       12. Tile method of claim 1, wherein the magnetic field is generated with a plurality of permanent magnets. 
     
     
       13. The method of claim 12, wherein the plurality of permanent magnets are fixed relative to the support, and wherein the step of moving the element comprises the step of intermittently passing a flux shunt member adjacent pole faces of the plurality of permanent magnets so as to provide a magnetic flux shunt path between the pole faces of the plurality of permanent magnets, to produce the varying magnetic field. 
     
     
       14. A method for generating a varying magnetic field to couple energy to a receiver coil implanted in an extremity of a patient, comprising the steps of: (a) generating a magnetic field with a plurality of magnets that are movable about the extremity of the patient;   (b) coupling a driving force to the plurality of magnets; and   (c) rotating the plurality of magnets around the extremity, thereby varying the magnetic field coupled to the receiver coil, variation of said magnetic field coupled to the receiver coil causing a varying electrical current to be induced in the implanted receiver coil.   
     
     
       15. A method for generating a varying magnetic field to couple energy to an implanted receiver coil, comprising the steps of: (a) generating a magnetic field;   (b) coupling a driving force to an element comprising at least one magnet so that the element is movable;   (c) moving the element with the driving force to vary the magnetic field coupled to the implanted receiver coil, variation of said magnetic field coupled to the implanted receiver coil causing a varying electrical current to be induced in the implanted receiver coil; and   (d) enhancing magnetic flux linkage between magnetic poles of said at least one permanent magnet and the implanted receiver coil by providing a flux linkage bar that couples a magnetic field from a pole of said at least one permanent magnet into the implanted receiver coil.